Probing microscopic chemical environments with high-intensity chirped pulses

By varying the chirp of high-intensity pulses, we can use the chirp-conditi on-dependent fluorescence yield to distinguish among different molecules or the same molecule in different microenvironments. As an example of the lat ter we show that SNAFL-2, a well-known pH-sensitive dye, shows large modula tion in fluorescence yield in response to both variation in acidity and var iation in chirp condition. Future applications of this as a novel contrast mechanism within fluorescence microscopy is discussed. (C) 1999 Optical Soc iety of America. OCIS codes: 050.1590, 170.2520, 260.2510, 320.2250, 320.71 30.